Industries, such as the electronics industry, have a need for analysis of industrial gases and other chemicals at very high purities with correspondingly low impurity levels. These levels have traditionally been at or below parts per million (ppm) by volume and are moving to parts per billion (ppb) by volume or parts per trillion (ppt) by volume for various impurity levels which can be tolerated in such gases or chemicals.
The electronics industry requires calibration gases for mass spectrometers, fourier transform infrared spectrometers and gas chromatographs. These calibration gases must have analytes in the ppm, ppb or ppt level by volume for the applications that they are utilized in for determining appropriate purity levels or emissions levels. The electronics industry also has the need for analysis of process tool emissions and subsequent containment devices, such as combustion chambers and water-based reactive gas removal systems.
The industry requires technology which allows for the generation of calibration gases having such low concentrations of analytes as standards where the standard is used at low pressure, in some instances below atmospheric pressure, the standard is a corrosive gas, or the standard is generated from a low volatility analyte source.
The industry has attempted to produce such standards such as is evidenced by U.S. Pat. No. 5,054,309 which dilutes a standard gas source with a raw gas in sequential series of steps to produce a low concentration gas mixture.
U.S. Pat. No. 5,214,952 describes a system for the production of ultra high purity calibration gas mixtures using mass flow controllers in a heated containment.
The prior art also includes systems such as depicted in FIG. 1 in which a diluent gas is mixed with a non corrosive gas or chemical in a permeation tube using mass flow controllers for the various process lines contained in an enclosure.
However, the prior art has not accomplished a dilution system for an array of gases or chemicals including non corrosive gases, low volatility gases or chemicals and corrosive gases in a manner providing for operator safety and low pressure delivery of low concentration calibration gas mixtures with necessary and appropriate purge functions for safety and purity assurance. These needs are solved by the present invention which will be set forth in greater detail below.